A Close Contact Tracing Method Based on Bluetooth Signals Applicable to Ship Environments

There are still outbreaks of COVID-19 across the world. Ships increase the risk of worldwide transmission of the virus. Close contact tracing remains as an effective method of reducing the risk of virus transmission. Therefore, close contact tracing in ship environments becomes a research topic. Exposure Notifications API (Application Programming Interface) can be used to determine the encountered location points of close contacts on ships. Location points of close contact are estimated by the encountered location points. Risky areas in ships can be calculated based on the encountered location points. The tracking of close contacts is possible with Bluetooth technology without the Internet. The Bluetooth signal can be used to judge the proximity among detecting devices by using the feature that Bluetooth has a strong signal at close range. This Bluetooth feature makes it possible to trace close contacts in ship environments. In this paper, we propose a method for close contact tracing and showing the risky area in a ship environment by combining beacon and Exposure Notification API using Bluetooth technology. This method does not require an Internet connection for tracing close contacts and can protect the personal information of close contacts. Copyright © 2023 KSII.

Qualitative study on psychological experience of close contacts with covid-19 during the centralized isolation medical observation period

To analyze the psychological experience of close contacts with COVID-19 during the centralized isolation medical observation (centralized isolation for short) period, 17 close contacts of COVID-19 who received medical isolation observation at designated locations in a city of China were selected by purposive sampling using qualitative study methods, and the interviewees were interviewed by full-coverage structured telephone. By analyzing the obtained data and summarizing the themes, it was found that the psychological status of the COVID-19 close contacts during the centralized isolation period could be classified into three themes: Obvious negative emotions, somatization of psychological problems, and demand for social support. During the epidemic, when close contacts were quarantined as high-risk groups, they often had complex and difficult psychological experiences. Relevant departments should actively carry out online guidance channels and offline knowledge dissemination, actively conduct psychological interventions for close contacts, assist them to develop life plans to enrich the life of the centralized isolation period. At the same time, relevant departments should do a good job in logistics and life support services, create a comfortable isolated living environment, and effectively relieve the negative emotions of close contacts of COVID-19 during centralized isolation through a variety of positive and effective measures to ensure physical and mental health. © 2023, Editorial department of Chinese Medical Ethics. All rights reserved.

Qualitative study on psychological experience of close contacts with covid-19 during the centralized isolation medical observation period

To analyze the psychological experience of close contacts with COVID-19 during the centralized isolation medical observation (centralized isolation for short) period, 17 close contacts of COVID-19 who received medical isolation observation at designated locations in a city of China were selected by purposive sampling using qualitative study methods, and the interviewees were interviewed by full-coverage structured telephone. By analyzing the obtained data and summarizing the themes, it was found that the psychological status of the COVID-19 close contacts during the centralized isolation period could be classified into three themes: Obvious negative emotions, somatization of psychological problems, and demand for social support. During the epidemic, when close contacts were quarantined as high-risk groups, they often had complex and difficult psychological experiences. Relevant departments should actively carry out online guidance channels and offline knowledge dissemination, actively conduct psychological interventions for close contacts, assist them to develop life plans to enrich the life of the centralized isolation period. At the same time, relevant departments should do a good job in logistics and life support services, create a comfortable isolated living environment, and effectively relieve the negative emotions of close contacts of COVID-19 during centralized isolation through a variety of positive and effective measures to ensure physical and mental health. © 2023, Editorial department of Chinese Medical Ethics. All rights reserved.

Effect of Lianhua Qingwen capsules on the positive rate of COVID-19 close contacts: A retrospective analysis of a large-scale population-based cohort study.

OBJECTIVE: Coronavirus disease 2019 (COVID-19) is still spreading worldwide. COVID-19 close contact is a key point of this epidemic. However, no medication is now available for close contact. This study aims to evaluate the beneficial effect and safety of the Lianhua Qingwen capsule (LHQW) on COVID-19 close contacts via a large, retrospective cohort study. METHODS: A total of 25,002 close contacts from 199 quarantine sites in Changchun, Jilin, who underwent medical observation, were included. The information about these close contacts were collected for further epidemiological research. Moreover, subjects were divided into an exposure group (LHQW group, oral, 4 capsules/time, t.i.d.; 18,579 subjects) and a non-exposure group (control group; 6,423 subjects). Inverse probability of treatment weighting (IPTW) with propensity score was employed to evaluate the positive rate of the SARS-CoV-2 nucleic acid test in nasal and throat swabs confirmed by polymerase chain reaction (PCR). RESULTS: A total of 22,975 subjects were included in the analysis, 17,286 cases in the LHQW group and 5,689 cases in the control group. The positive rate of nucleic acid testing in the LHQW group was 5.12%, and that in the control group was 9.70% before the adjustment of IPTW of the propensity score; the difference between the two groups was -4.58% (95% CI -5.44- -3.77%, p <  0.001). After adjusting IPTW, the positive rate of nucleic acid testing in the LHQW group and the control group was 5.10% and 9.80%, respectively; the difference between the two groups was -4.70% (95% CI -5.18- -4.23, p < 0.001). The conclusions before and after the IPTW adjustment were consistent. No test drug-related adverse reactions were observed during the study period. CONCLUSION: LHQW has a beneficial effect and safety on the close contacts of SARS-CoV-2 who are under medical observation at the quarantine sites and can be used as an optional drug for those close contacts.

Infection rate and factors affecting close contacts of COVID-19 cases: A systematic review.

OBJECTIVE: Contact tracing plays an essential role in mitigating the impact of an epidemic. During the COVID-19 pandemic, studies of those who have been in close contact with confirmed cases offer critical insights to understand the epidemiological characteristics of SARS-CoV-2 better. This study conducts a meta-analysis of existing studies' infection rates and affecting factors. METHODS: We searched PubMed, Web of Science and CNKI from the inception to April 30 2022 to identify systematic reviews. Two reviewers independently extracted the data and assessed risk of bias. Meta-analyses were conducted to calculate pooled estimates by using Stata/SE 15.1 software. RESULTS: There were 47 studies in the meta-analysis. Among COVID-19 close contacts, older age (RR = 1.94, 95% CI: 1.70, 2.21), contacts in households (RR = 2.83, 95% CI: 2.20, 3.65), and people in close contact with symptomatic infections (RR = 3.62, 95% CI: 1.88, 6.96) were associated with higher infection rates. CONCLUSION: On average, each primary infection corresponded to 5.8 close contacts. Among COVID-19 close contacts, older age and contacts in households were associated with higher infection rates, and people in close contact with symptomatic infections had three times higher risk of infection compared to people in close contact with asymptomatic infections. In general, there are significantly more studies from China about close contacts, and the infection rate among close contacts was lower compared to other countries.

How to reduce the exposure risk of medical staff from SARS-CoV-2 by reducing environmental contamination: Experience from designated hospitals in China.

Background: Using daily monitoring of environmental surfaces and personal protective equipment (PPE), we found an increase in environmental contamination since August 18, 2021, in a designated hospital for COVID-19 patients in China, which may lead to an increased risk of exposure to medical staff. Methods: To investigate the cause of increased environmental contamination and effect of our intervention, we obtained environmental samples at pre-intervention (August 18-21, 2021) and post-intervention (August 22-28, 2021) from six infection isolation rooms with windows for ventilation and other auxiliary areas at 105 and 129 sites before routine daily cleaning, respectively. In addition, we obtained PPE samples from 98 medical staff exiting the patient rooms/contaminated areas at 482 sites. Between August 22 and 24, 2021, we took measures to reduce environmental contamination based on sampling and inspection results. Findings: At pre-intervention, the positivity rates for contamination of environmental surfaces and PPE samples were significantly higher for critical patients (37.21 and 27.86%, respectively) than severely ill patients (25.00 and 12.50%, respectively) and moderately ill patients (0.00 and 0.00%, respectively) (Pearson's Chi-square: χ2 = 15.560, p = 0.000; Fisher's exact test: χ2 = 9.358, p = 0.007). Therefore, we inferred that the source of contamination of environmental surfaces and PPE was mainly the room of critically ill patients, likely through the hands of medical staff to the potentially contaminated areas. A critically ill patient had emergency tracheal intubation and rescue on August 18, 2021, due to worsened patient condition. The ventilator tube used for first aid did not match the ventilator, and the ventilator tube fell off multiple times on August 18-21, 2021, which may explain the increased contamination of environmental surfaces and PPE from critically ill patients, as well as lead to indirect contamination of potentially contaminated areas. The contamination positivity rates of environmental surfaces and PPE were reduced by replacing the appropriate ventilator catheter, limiting the number of people entering the isolation room simultaneously, increasing the frequency of environmental disinfection, standardizing the undressing process, setting up undressing monitoring posts to supervise the undressing process, and preventing the spread of virus infections in the hospital during an epidemic. Conclusions: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was spread on object surfaces in isolation rooms mainly by touch, and the contamination of environmental surfaces and PPE was greater in rooms of patients with greater disease severity and higher surface touch frequency. Therefore, strict protective measures for medical staff, frequent environmental cleaning for isolation rooms, and compliance with mask wearing by patients when conditions permit should be advised to prevent SARS-CoV-2 spread in hospitals.

A QGIS Plugin to monitor proximities in surveillance videos

Quantum Geographic Information System (QGIS) is a topographical system that processes spatial data. Popular spatial algorithms such as spatial join, clipping, area computations and visualizations are implemented either as a basic support or through additional Plugins designed with Python modules. These features are not yet available for video input in QGIS. With the current Covid-19 pandemic outbreak the non-pharmaceutical precautionary measures suggested by the World Health Organization is to wear mask and maintain minimum physical proximity between the two individuals. The proposed system processes the surveillance video captured through CCTV cameras from college campus, detects the persons from the video and computes the physical proximity between people in the captured spaces. The proposed approach also provides important information about individual person getting in contact with how many other people in the given time duration thereby identifying hotspots in the overall spatial expanse. The module is integrated as a plugin in QGIS which is a contribution to the open source software. © 2022 IEEE.

THE DYNAMIC EFFECTS OF DIFFERENT QUARANTINE MEASURES ON THE SPREAD OF COVID-19

COVID-19 is pandemic worldwide, and different countries have adopted different measures to stop the spread of the epidemic. In order to study the impact of quarantining close contacts on the spread of coronavirus disease 2019 (COVID-19), based on data published by Beijing Municipal Health Commission, World Health Organization (WHO) and Korea Central Disaster Control Headquarters (KCDC), SEIR dynamic models of virus transmission in Beijing and South Korea were set up respectively;the Genetic algorithm was used to fit the important parameters such as transmission rate, recovery rate and quarantine rate;calculated the control reproduction number;we discuss the impact of quarantining close contacts on daily new cases in South Korea, the daily new cases decrease after a week, and drop to 16.93 after 30 days. When close contacts were quarantined, the maximum value of daily new cases Imax = 57.4 obtained by simulation is only 13% of the actual maximum value actual Imax = 441;the influences of different quarantine rates and the number of the susceptible on the number of daily new cases are also discussed, the quarantine of close contacts has significant effect on reducing the number of daily new cases compared with less stringent control measures. Vigorous control measures reduce the number of daily new cases to single digits in just 17 days in Beijing, effectively curbing the transmission of COVID-19. It has vital significance for the prevention and control of the epidemic in other countries and regions. © 2022, Wilmington Scientific Publisher. All rights reserved.

Institutional development and the government response to COVID-19 in China.

As COVID-19 is pervasive across the globe, governments in different countries face the dilemma of restricting the transmission risk of the virus by social distancing while yet maintaining economic activity. Inadequate social distancing policies lead to more infection cases and deaths, while over stringent social distancing policies have significant economic cost implications. This study investigates the role of local government institutions in striking the balance between saving lives and economic recovery. We based our study on a sample of 28 provincial governments in China during the early outbreak of 2020 when the emergency responses of local governments were synchronous. The findings show that local governments in those provinces with lower degrees of marketization, which were accustomed to directly intervene in the social system, mandatorily quarantined many more close contacts for each confirmed case than those in the more market-oriented provinces whose social distancing policies took economic considerations into account. The 'overdone' (over stringent) social distancing policies in the more state-oriented provinces led to lower human mobility and economic growth. This study highlights the importance of taking economic considerations into account when adopting policies and strategies to combat the spread of COVID-19 and how different institution management cultures lead to different outcomes.

Using the Theory of Motivated Information Management to Understand Direct Information Seeking on COVID-19 from Close Contacts

INTRODUCTION: As the COVID-19 pandemic spread like wildfire in 2020, initially, little was known about the pandemic. Various parties including local governments, health agencies, medical researchers, and frontliners made concerted efforts to ensure the accuracy, timeliness, and reliability of the information released to the public. Accordingly, a major focus of this study is to examine the factors influencing COVID-19 direction information seeking from close contacts as determined by the theory of motivated information management (TMIM). MATERIALS AND METHODS: A cross-sectional survey using Google form was distributed to undergraduate students pursuing communication courses at public universities in Malaysia. RESULTS: Out of six hypotheses, only two are not supported. Consistent with TMIM, outcome expectancy and target efficacy predict direct information seeking on COVID-19 from close contacts. Further, target efficacy mediates the relationship between outcome expectancy and direct information seeking. CONCLUSION: Overall, the study found empirical support for TMIM as a useful framework for understanding COVID-19 information management. The repercussions of these findings on TMIM as well as key factors that may influence decision-making on information seeking during a global health pandemic are also discussed. © 2022. IIUM Medical Journal Malaysia. All Rights Reserved.

COVID-19 contact tracing in the hospitals located in the North Denmark region: A retrospective review.

Background: The Department of Infection Control, at our University Hospital conducted contact tracing of COVID-19 positive patients and staff members at all hospitals in the North Denmark Region. Aim: To describe the contact tracing performed during the COVID-19 pandemic in the Region and its outcomes. Methods: Data from each contact tracing were collected prospectively during 14 May 2020-26 May 2021. Data included information about the index case (patient or hospital staff member), presentation (asymptomatic vs symptomatic), probable source of transmission (community-acquired or hospital-acquired), number of close contacts and if any of these were SARS-CoV-2 PCR-test positive. Findings: 362 contact tracing were performed. A total of 573 COVID-19 positive cases were identified among 171 (30%) patients and 402 (70%) staff members. 192 (34%) of all cases were tested due to symptoms of COVID-19, whereas two-third were tested for other reasons including outbreak and systematic screening tests. A total of 1575 close contacts were identified, including 225 (14%) patients and 1350 (86%) staff members. 100 (6%) close contacts, including 24 patients and 76 staff members, were infected with SARS-CoV-2, of which 33 (43%) staff members was positive at day 0 i.e. the same day as being identified as close contacts. Discussion: We found a three to one of close contacts to each index case, but only 6% became SARS-CoV-2 positive, with a surprisingly high number of those identified at day 0. Our data confirm that regular testing of patients and staff will identify asymptomatic carriers and thereby prevent new cases.

Family clustering of SARS-CoV-2 in Qazvin, Northwest of Iran.

Background: Human infection affected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been recognized as a global health concern. We report the epidemiological and clinical characteristics of patients with a familial cluster of SARS-CoV-2 from Qazvin province (located in the northwest of Iran). Methods: In this cross-sectional study, we enrolled 332 hospitalized patients that were confirmed SARS-CoV-2 diseases with laboratory-based (PT-PCR) test in Qazvin province, Iran. Having family infection transmission and subsequently, family clustering of SARS-COV-2 disease was assessed with the Generalized Estimating Equation model in patients. Results: Crude odds ratio estimates of creating family clustering of SARS-CoV-2 infection was 0.47 times [95% CI: 0.23, 0.98, p=0.045] less for female compared to the males; 2.26 [95% CI: 1.11, 4.58, p=0.024] and 2.69 [95% CI: 1.47, 4.93, p=0.001] for SARS-CoV-2 patients that had digestive and muscle pain in comparison with those did not this mentioned symptoms, respectively. 1.52 [95% CI: 1.05, 2.23, p=0.024] for patients with a longer hospitalization compared with patients that had shorter duration of hospitalization and adjusted odds ratio estimates were 2.13 [95% CI: 1.12, 4.03, p=0.020] for patients who receive public health services in comparison those did not receive public health services. Conclusion: Our findings confirm the person-to-person transmission of this novel coronavirus in family settings and hospitals, and the reports of infected travelers in other geographical regions. Major gaps in our knowledge about the potential factors in creating family clustering of SARS-CoV-2 infection, epidemiology, duration of human transmission and etc. need fulfillment by future studies.

The Positive Rate of Nucleic Acid Testing and the Epidemiological Characteristics of COVID-19 in Chongqing.

OBJECTIVE: The purpose of this study is to analyze the positive rate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid testing (NAT), cases of and deaths due to SARS-CoV-2, and the epidemiological characteristics of SARS-CoV-2 to identify high-risk populations. METHODS: A retrospective study in Jiulongpo district of Chongqing was conducted by performing continuous observations of the frequency of SARS-CoV-2 NAT, analyzing the data of close contacts of patients and asymptomatic carriers, and collecting epidemiological data. Data were collected from January 20, 2020, when the first case of SARS-CoV-2 infection was reported, to March 26, 2020. Descriptive statistical analysis and Cochrane-Mantel-Haenszel analysis were used to compare the positive detection rates and positive diagnostic rates of different exposure groups. RESULTS: A total of 7,118 people received 10,377 SARS-CoV-2 nucleic acid tests in one district, and the SARS-CoV-2 positive rates were 0.40% (18/4446) and 0.15% (4/2672) in people receiving one and ≥ two nucleic acid tests (p = 0.06), respectively. Those with suspected cases (12.35%) and close contacts (8%) had higher positive rates than people tested at fever clinics (0.39%) (p < 0.001). The median latency (range) of cases was 5 (2, 9) days, and the median time from diagnosis to recovery was 22 (14, 25) days. One recovered patient received a positive test result at 28 days after recovery when she attempted to donate blood. Six clustered cases, including one patient who died, indicated persistent human-to-human transmission. One patient who was diagnosed after death was found to have infected 13 close contacts. People working in catering and other public service departments (36.36%) and people who are unemployed and retirees (45.45%) have an increased risk of infection compared with technical staff (9.09%) and farmers (9.09%). CONCLUSION: The total positive rate was low in the tested population, and more effective detection ranges should be defined to improve precise and differentiated epidemic control strategies. Moreover, in asymptomatic carriers, SARS-CoV-2 tests were positive after recovery, and patients with suspected SARS-CoV-2 infection who die may pose serious potential transmission threats.

Adherence and Association of Digital Proximity Tracing App Notifications With Earlier Time to Quarantine: Results From the Zurich SARS-CoV-2 Cohort Study.

Objectives: We aimed to evaluate the effectiveness of the SwissCovid digital proximity tracing (DPT) app in notifying exposed individuals and prompting them to quarantine earlier compared to individuals notified only by manual contact tracing (MCT). Methods: A population-based sample of cases and close contacts from the Zurich SARS-CoV-2 Cohort was surveyed regarding SwissCovid app use and SARS-CoV-2 exposure. We descriptively analyzed app adherence and effectiveness, and evaluated its effects on the time between exposure and quarantine among contacts using stratified multivariable time-to-event analyses. Results: We included 393 SARS-CoV-2 infected cases and 261 close contacts. 62% of cases reported using SwissCovid and among those, 88% received and uploaded a notification code. 71% of close contacts were app users, of which 38% received a warning. Non-household contacts notified by SwissCovid started quarantine 1 day earlier and were more likely to quarantine earlier than those not warned by the app (HR 1.53, 95% CI 1.15-2.03). Conclusion: These findings provide evidence that DPT may reach exposed contacts faster than MCT, with earlier quarantine and potential interruption of SARS-CoV-2 transmission chains.

Facilities for Centralized Isolation and Quarantine for the Observation and Treatment of Patients with COVID-19.

The coronavirus disease 2019 (COVID-19) pandemic increased the burden on many healthcare systems and in the process, exposed the need for medical resources and physical space. While few studies discussed the efficient utilization of medical resources and physical space so far. Therefore, this study aimed to summarize experiences related to facilities used for centralized isolation for medical observation and treatment during the COVID-19 pandemic in China and to provide suggestions to further improve the management of confirmed cases, suspected cases, and close contacts. In China, three types of facilities for centralized isolation (Fangcang shelter hospitals, refitted non-designated hospitals, and quarantine hotels) underwent retrofitting for the treatment and isolation of confirmed and suspected cases. These facilities mitigated the immediate high demand for space. Moreover, in order to minimize infection risks in these facilities, regulators and governmental agencies implemented new designs, management measures, and precautionary measures to minimize infection risk. Other countries and regions could refer to China's experience in optimally allocating social resources in response to the COVID-19 pandemic. As a conclusion, government should allocate social resources and construct centralized isolation and quarantine facilities for an emergency response, health authorities should issue regulations for centralized isolation facilities and pay strict attention to the daily management of these facilities, a multidisciplinary administration team is required to support the daily operation of a centralized isolation facility, in-depth studies and international collaboration on the centralized isolation policy are encouraged.

[Epidemic Characteristics of the Novel Coronavirus Delta Variant in Guangzhou and Grid Crowd Management Based on Public Security Forensic Perspective].

ABSTRACT: Abstract： Objective To analyze the first epidemic spread of the novel coronavirus Delta variant in China based on public security forensic perspective, investigate its transmission characteristics, contributing factors, and epidemiologic research experience, and provide a reference for the prevention and control of the epidemic caused by the novel coronavirus variant. Methods Based on the information that public security forensic experts obtained from front-line epidemiologic research, the gender, age, place of residence, transmission route and infectivity of the coronavirus disease 2019 （COVID-19） confirmed cases, asymptomatic infected persons and their close contacts in Guangzhou caused by the novel coronavirus Delta variant were analyzed. The basic reproduction number （R0） during this epidemic in Guangzhou was calculated. Results Among the 153 cases infected with novel coronavirus Delta variant in the epidemic, 63 cases were male and 90 cases were female, their age ranging from 1 to 92 years, with a median age of 49 years. The main route of transmission was close contact, including dining together, co-living, and close contact in the same residential building. There were 31 cases of family clusters, 25 of which were in Liwan District. The epidemic lasted from May 26 to May 29, and the R0 remained above 4.0. After May 30, R0 began to decline and remained below 1.0 from June 7. Conclusion The novel coronavirus Delta variant is highly infectious, the crowd is generally susceptible to infection and family cluster cases are easy to occur. So, it is necessary to precisely prevent and control this strain. Public security forensic experts have both medical literacy and criminal investigation capabilities, they can play a more professional role in epidemic prevention and control.

[Moxibustion on mental disorder in close contacts of coronavirus disease 2019: a randomized controlled trial].

OBJECTIVE: To observe the effect of moxibustion combined with Daiwenjiu plaster on mental disorder and self rating symptoms in close contacts of coronavirus disease 2019 (COVID-19) during quarantine. METHODS: A total of 240 close contacts of COVID-19 were randomized into an observation group (120 cases, 18 cases dropped off) and a control group (120 cases, 58 cases dropped off). Conventional observation was adopted in the control group. Moxibustion combined with Daiwenjiu plaster was given in the observation group, moxibustion was applied at Zusanli (ST 36), Hegu (LI 4) and Shenque (CV 8), 10 min each acupoint, once a day; Daiwenjiu plaster was applied at Dazhui (GV 14) and Feishu (BL 13) for 3 to 6 h each time, once every 2 days, the treatment was required for 2 weeks. Before and after treatment and in the follow-up of 2 weeks after treatment, self-reporting questionnaire 20 (SRQ-20), self-rating anxiety scale (SAS) scores and self rating symptoms were evaluated in the two groups. RESULTS: In the follow-up, SRQ-20 score was decreased compared before treatment (P<0.01), SAS score was decreased compared before and after treatment (P<0.01, P<0.05) in the observation group. After treatment and in the follow-up, SRQ-20 scores in the observation group were lower than those in the control group (P<0.05, P<0.01). After treatment, the case proportion of fatigue in the observation group was higher than that in the control group (P<0.05). In the follow-up, the case proportion of tension was lower than that in the control group (P<0.05). CONCLUSION: Moxibustion combined with Daiwenjiu plaster can effectively improve the mental disorder in close contacts of COVID-19.

Transmission of COVID-19 and its Determinants among Close Contacts of COVID-19 Patients Running title.

BACKGROUND: This study aimed to determine the secondary attack rate (SAR) and its determinants to describe the clinical features and epidemiological aspects of patients and determine the risk factors of COVID-19 among household contacts in Hamadan Province, west of Iran. STUDY DESIGN: A cohort study. METHODS: In this cohort study, a total of 323 index cases and 989 related close contacts ages more than 15 years old (family members, relatives, and co-workers) were enrolled using a manual contact tracing approach, and all participants were tested by reverse transcription polymerase chain reaction test. In this research, the frequency of symptoms was assessed, the SAR among contacts of index cases was calculated, and the risk factors of COVID-19 were evaluated by the logistic regression model. RESULTS: The secondary attack rate for total household members of index cases was estimated at 31.7% (95% CI: 28.8-34.7). It was found that among household contacts, the highest SARs were related to spouses 47.1% (95% CI: 38.7-55.7) and grandparents/parents 39.3% (95% CI: 29.4, 49.9) of index cases, who had also higher risks to become secondary cases (adjusted odds ratio [OR]=2.98, 95% CI: 1.31-6.75 and adjusted OR=2.76, 95% CI: 1.18-6.44, respectively). Considering the occupation of contacts, unemployed and retired people and housewives were most susceptible for transmission of COVID-19. It was revealed that cough was the most prevalent symptom among index and secondary cases. CONCLUSION: Our findings indicated that spouses and grandparents/parents of index cases were the most susceptible individuals for COVID-19 transmission. Prolonged exposure with index case before COVID-19 diagnosis raised the chance of infection among secondary cases.

Seroprevalence of SARS-CoV-2-Specific Antibodies among Quarantined Close Contacts of COVID-19 Patients, Faroe Islands, 2020.

Close contacts of coronavirus disease (COVID-19) patients are at high risk for severe acute respiratory syndrome 2 (SARS-CoV-2) infection. We assessed the seroprevalence of SARS-CoV-2-specific antibodies among quarantined close contacts of COVID-19 patients in the Faroe Islands. We invited quarantined close contacts of COVID-19 index patients identified during March 3-April 22, 2020, to participate in this study; 584 (81%) contacts consented and underwent serologic testing. Among the 584 participants, 32 (5.5%) were seropositive for total antibody against SARS-CoV-2. Household and young or elderly contacts had higher risk for seropositivity than other contacts. We found a secondary attack rate of 19.2%. Seroprevalence among close contacts was almost 10-fold higher than among the general population of the Faroe Islands. Regularly testing household close contacts of COVID-19 patients might help track the transmission of SARS-CoV-2.

Can the cycle threshold (Ct) value of RT-PCR test for SARS CoV2 predict infectivity among close contacts?

BACKGROUND: COVID-19 global pandemic is an unprecedented health emergency. Rapid identification and isolation of infected individuals is crucial. Qatar's National Health Strategic Command Group adopted a cut off 30 for Ct value of RT-PCR result of a positive case to decide on duration of isolation and quarantine period for their close contacts. AIM: To test if Ct value cut off 30 reflects on the infectivity potential among close contacts. METHODOLOGY: All positive cases reported during July' 2020 whose contacts had been traced and swabbed were extracted from database after removing personal identifiers. Close-contact was defined as anybody who has been within 2 m distance of a confirmed positive case for 15 min or more, without any personal protection equipment. Descriptive analysis was done and test of significance of difference in positivity among the contacts of those with ct < 30 and >30 was done. RESULTS: 2308 COVID-19 positive cases were followed up. More than three-quarters had a Ct value < 30, with a mean Ct value of 24.05(+6.48). On an average 6 contacts were swabbed per case. More than half the positive cases followed up had at least one secondary case, with median positivity rate 12.5%. A significant relation was noted between Ct value cut-off 30 and secondary transmission (1.5 times more risk among those with Ct value < 30). A significant difference was noted in median positivity rate between close contacts of positive cases with Ct value > 30 or <30. CONCLUSION: Further studies combining PCR assays, culture studies and contact tracing are needed to define which factors can be used to reliably predict the infectious status of patients with COVID-19.